infectious diseases

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Health experts plead for unvaxxed Americans to get measles shot as cases rise

American Medical Association, CDC, children, health, health advisory, infectious diseases, measles, Science, travel, vaccination, vaccines / /

MMR is safe and effective —

The US hit last year’s total in under 12 weeks, suggesting we’re in for a bad time.

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A view from a hospital as children receiving medical treatment, in capital Kabul, Afghanistan on April 18, 2022. More than 130 children have died from the measles in Afghanistan since the beginning of this year.

Enlarge / A view from a hospital as children receiving medical treatment, in capital Kabul, Afghanistan on April 18, 2022. More than 130 children have died from the measles in Afghanistan since the beginning of this year.

The Centers for Disease Control and Prevention and the American Medical Association sent out separate but similar pleas on Monday for unvaccinated Americans to get vaccinated against the extremely contagious measles virus as vaccination rates have slipped, cases are rising globally and nationally, and the spring-break travel period is beginning.

In the first 12 weeks of 2024, US measles cases have already matched and likely exceeded the case total for all of 2023. According to the CDC, there were 58 measles cases reported from 17 states as of March 14. But media tallies indicate there have been more cases since then, with at least 60 cases now in total, according to CBS News. In 2023, there were 58 cases in 20 states.

“As evident from the confirmed measles cases reported in 17 states so far this year, when individuals are not immunized as a matter of personal preference or misinformation, they put themselves and others at risk of disease—including children too young to be vaccinated, cancer patients, and other immunocompromised people,” AMA President Jesse Ehrenfeld said in a statement urging vaccination Monday.

The latest data indicates that vaccination rates among US kindergarteners have slipped to 93 percent nationally, below the 95 percent target to prevent the spread of the disease. And vaccine exemptions for non-medical reasons have reached an all-time high.

The CDC released a health advisory on Monday also urging measles vaccination. The CDC drove home the point that unvaccinated Americans are largely responsible for importing the virus, and pockets of unvaccinated children in local communities spread it once it’s here. The 58 measles infections that have been reported to the agency so far include cases from seven outbreaks in seven states. Most of the cases are in vaccine-eligible children aged 12 months and older who are unvaccinated. Of the 58 cases, 54 (93 percent) are linked to international travel, and most measles importations are by unvaccinated US residents who travel abroad and bring measles home with them, the CDC flagged.

The situation is likely to worsen as Americans begin spring travel, the CDC suggested. “Many countries, including travel destinations such as Austria, the Philippines, Romania, and the United Kingdom, are experiencing measles outbreaks,” the CDC said. “To prevent measles infection and reduce the risk of community transmission from importation, all US residents traveling internationally, regardless of destination, should be current on their [measles-mumps-rubella (MMR)] vaccinations.” The agency added in a recommendation to parents that “even if not traveling, ensure that children receive all recommended doses of MMR vaccine. Two doses of MMR vaccine provide better protection (97 percent) against measles than one dose (93 percent). Getting MMR vaccine is much safer than getting measles, mumps, or rubella.”

For Americans who are already vaccinated and communities with high vaccination coverage, the risk is low, the CDC noted. “However, pockets of low coverage leave some communities at higher risk for outbreaks.” This, in turn, threatens wider, continuous spread that could overturn the country’s status of having eliminated measles, which was declared in 2000. The US was close to losing its elimination status in 2019 when outbreaks among unvaccinated children drove 1,247 cases across 31 states. Vaccination rates have only fallen since then.

“The reduction in measles vaccination threatens to erase many years of progress as this previously eliminated vaccine-preventable disease returns,” the AMA’s Ehrenfeld warned.

As Ars has reported previously, measles is among the most contagious viruses known and can linger in airspace for up to two hours. Up to 90 percent of unvaccinated people exposed will contract it. Symptoms can include high fever, runny nose, red and watery eyes, and a cough, as well as the hallmark rash. About 1 in 5 unvaccinated people with measles are hospitalized, while 1 in 20 infected children develop pneumonia, and up to 3 in 1,000 children die of the infection. Brain swelling (encephalitis) can occur in 1 in 1,000 children, which can lead to hearing loss and intellectual disabilities. The virus can also destroy immune responses to previous infections—a phenomenon known as “immune amnesia”—which can leave children vulnerable to various other infections for years afterward.

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“Very sick” pet cat gave Oregon resident case of bubonic plague

bubonic plague, cat, CDC, fleas, infection, infectious diseases, Oregon, plague, rodents, Science, yersinia pestis / /

Surprise plague —

The person’s cat was reportedly extremely ill and had a draining abscess.

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A cat, but not the one with plague.

Enlarge / A cat, but not the one with plague.

An Oregon resident contracted bubonic plague from their “very sick” pet cat, marking the first time since 2015 that someone in the state has been stricken with the Black Death bacterium, according to local health officials.

Plague bacteria, Yersinia pestis, circulates cryptically in the US in various types of rodents and their fleas. It causes an average of seven human cases a year, with a range of 1 to 17, according to the Centers for Disease Control and Prevention. The cases tend to cluster in two regions, the CDC notes: a hotspot that spans northern New Mexico, northern Arizona, and southern Colorado, and another region spanning California, far western Nevada, and southern Oregon.

The new case in Oregon occurred in the central county of Deschutes. It was fortunately caught early before the infection developed into a more severe, systemic bloodstream infection (septicemic plague). However, according to a local official who spoke with NBC News, some doctors felt the person had developed a cough while being treated at the hospital. This could indicate progression toward pneumonic plague, a more life-threatening and more readily contagious variety of the plague that spreads via respiratory droplets. Nevertheless, the person’s case reportedly responded well to antibiotic treatment, and the person is recovering.

Health officials worked to prevent the spread of the disease. “All close contacts of the resident and their pet have been contacted and provided medication to prevent illness,” Richard Fawcett, Deschutes County Health Officer, said in a news release.

Fawcett told NBC News that the cat was “very sick” and had a draining abscess, indicating “a fairly substantial” infection. The person could have become infected by plague-infected fleas from the cat or by handling the sick cat or its bodily fluids directly. Symptoms usually develop two to eight days after exposure, when the infection occurs in the lymph nodes. Early symptoms include sudden onset of fever, nausea, weakness, chills, muscle aches, and/or visibly swollen lymph nodes called buboes. If left untreated, the infection progresses to the septicemic or pneumonic forms.

It’s unclear how or why the cat became infected. But cats are particularly susceptible to plague and are considered a common source of infection in the US. The animals, when left to roam outdoors, can pick up infections from fleas as well as killing and eating infected rodents. Though dogs can also pick up the infection from fleas or other animals, they are less likely to develop clinical illness, according to the CDC.

While plague cases are generally rare in the US, Deschutes County Health Services offered general tips to keep from contracting the deadly bacteria, namely: Avoid contact with fleas and rodents, particularly sick, injured, or dead ones; Keep pets on a leash and protected with flea control products; Work to keep rodents out and away from homes and other buildings; and avoid areas with lots of rodents while camping and hiking and wear insect repellant when outdoors to ward off fleas.

According to the CDC, there were 496 plague cases in the US between 1970 and 2020. And between 2000 and 2020, the CDC counted 14 deaths.

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Contact-tracing software could accurately gauge COVID-19 risk

Biology, COVID-19, epidemiology, infectious diseases, SARS-CoV-2, Science / /

As it turns out, epidemiology works —

Time spent with infected individuals is a key determinant of risk.

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A woman wearing a face mask and checking her phone.

It’s summer 2021. You rent a house in the countryside with a bunch of friends for someone’s birthday. The weather’s gorgeous that weekend, so mostly you’re all outside—pool, firepit, hammock, etc.—but you do all sleep in the same house. And then on Tuesday, you get an alert on your phone that you’ve been exposed to SARS-CoV-2, the virus that causes COVID-19. How likely are you to now have it?

To answer that question, a group of statisticians, data scientists, computer scientists, and epidemiologists in the UK analyzed 7 million people who were notified that they were exposed to COVID-19 by the NHS COVID-19 app in England and Wales between April 2021 and February 2022. They wanted to know if—and how—these app notifications correlated to actual disease transmission. Analyses like this can help ensure that an app designed for the next pathogen could retain efficacy while minimizing social and economic burdens. And it can tell us more about the dynamics of SARS-CoV-2 transmission.

Over 20 million quarantine requests

The NHS COVID-19 app was active on 13 to 18 million smartphones per day in 2021. It used Bluetooth signals to estimate the proximity between those smartphones while maintaining privacy and then alerted people who spent 15 minutes or more at a distance of 2 meters or less from a confirmed case. This led to over 20 million such alerts, each of which came with a request to quarantine—quite a burden.

The researchers found that the app did, in fact, accurately translate the duration and proximity of a COVID-19 exposure to a relevant epidemiological risk score. The app assessed a contact’s risk by multiplying the length of contact, the proximity of contact, and the infectiousness of the index case as determined by how long it had been since the index case started showing symptoms or tested positive.

There was an increasing probability of reported infection as the app’s risk score increased: more contacts whom the app deemed were at a high transmission risk did go on to test positive for COVID-19 within the following two weeks than those who were notified but had lower risk levels. (That’s positive tests that were reported by using the app. Some of the high-risk people probably did not test at all, did not report their test results, or did not report them within the allotted time. So this is an underestimation of the correlation between notification of risk and infection.)

More exposure = higher risk

When the researchers separated the factors contributing to the risk of an exposure, they found that duration was the most important indicator. Household exposures accounted for 6 percent of all contacts but 41 percent of transmissions.

One caveat: The app didn’t record any contextual variables that are known to impact transmission risk, like if people live in an urban or rural area, was the meeting indoors or outdoors, was it during the week or over the weekend, was anyone vaccinated, etc. Including such data could make risk assessment more accurate.

Based on their work, the researchers suggest that an “Amber Alert” stage could have been introduced to the app, in which people deemed to have an interim degree of risk would be guided to get a PCR test rather than immediately jumping to quarantine. Including this intermediate Amber Alert population could have significantly reduced the socioeconomic costs of contact tracing while retaining its epidemiological impact or could have increased its effectiveness for a similar cost. Performing analyses like this early on in the next pandemic to determine how it is transmitted might minimize illness and strain on society.

Nature, 2023.  DOI:  10.1038/s41586-023-06952-2

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